bug#40632: Emacs freezes when a wrap-prefix is longer than the frame with

[Clément Pit-Claudel]

Hi all,

After running the following snippet, resizing my Emacs frame to be narrower 
than ~18 characters causes Emacs to freeze.  This seems to be because the 
wrap-prefix is too wide to be displayed unbroken.

(with-current-buffer (get-buffer-create "*wrap*")
  (visual-line-mode)
  (dotimes (_ 50)
    (insert "Some long prefix: ")
    (insert (propertize "Some text that wraps, thanks to a wrap-prefix property"
                        'wrap-prefix "                  "))
    (insert "\n")
    (pop-to-buffer (current-buffer))))

Clément.

In GNU Emacs 28.0.50 (build 5, x86_64-pc-linux-gnu, GTK+ Version 3.22.30, cairo 
version 1.15.10)
 of 2020-03-15 built on clem-w50-mint
Repository revision: 9dccaf8a5cdb10dae597345ec3741475477a7d97
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.11906000
System Description: Linux Mint 19.3

Recent messages:
nil [5 times]
Quit
Mark set
nil
delete-backward-char: Text is read-only
<left-fringe> <mouse-1> is undefined
Quit
Entering debugger...
Quit [3 times]
C-x <down> is undefined
Quit
Configured features:
XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND GPM DBUS GSETTINGS GLIB NOTIFY
INOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE HARFBUZZ M17N_FLT LIBOTF
ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM MODULES THREADS LIBSYSTEMD
JSON PDUMPER LCMS2 GMP

Important settings:
  value of $LC_MONETARY: en_DK.UTF-8
  value of $LC_NUMERIC: en_DK.UTF-8
  value of $LC_TIME: en_DK.UTF-8
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Fundamental

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  visual-line-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
format-spec rfc822 mml mml-sec password-cache epa derived epg epg-config
gnus-util rmail rmail-loaddefs text-property-search mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail
rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils thingatpt
cl-extra seq byte-opt gv bytecomp byte-compile cconv time-date subr-x
help-fns radix-tree cl-print debug backtrace help-mode easymenu
find-func cl-loaddefs cl-lib tooltip eldoc electric uniquify ediff-hook
vc-hooks lisp-float-type mwheel term/x-win x-win term/common-win x-dnd
tool-bar dnd fontset image regexp-opt fringe tabulated-list replace
newcomment text-mode elisp-mode lisp-mode prog-mode register page
tab-bar menu-bar rfn-eshadow isearch timer select scroll-bar mouse
jit-lock font-lock syntax facemenu font-core term/tty-colors frame
minibuffer cl-generic cham georgian utf-8-lang misc-lang vietnamese
tibetan thai tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek
romanian slovak czech european ethiopic indian cyrillic chinese
composite charscript charprop case-table epa-hook jka-cmpr-hook help
simple abbrev obarray cl-preloaded nadvice loaddefs button faces
cus-face macroexp files text-properties overlay sha1 md5 base64 format
env code-pages mule custom widget hashtable-print-readable backquote
threads dbusbind inotify lcms2 dynamic-setting system-font-setting
font-render-setting cairo move-toolbar gtk x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 61654 7334)
 (symbols 48 6844 1)
 (strings 32 19732 2278)
 (string-bytes 1 597700)
 (vectors 16 12162)
 (vector-slots 8 157989 11950)
 (floats 8 30 206)
 (intervals 56 1244 16)
 (buffers 1000 16))